Import Sets, Data Sources, and Transform Maps
Data import uses data sources (file, LDAP, JDBC, REST), import sets (sys_import_set), staging tables (sys_import_set_row or custom staging), transform maps, and coalesce fields. Candidates must understand the flow: load data into a staging table, then run a transform map to move rows into the target table. Field maps map source columns to target fields; transform scripts (onBefore, onAfter) handle logic. Coalesce fields determine whether a row inserts a new record or updates an existing one.
Know import set cleanup (staging tables can grow; schedule cleanup), transform history (sys_transform_entry), and scheduled imports (via scheduled jobs or import set scheduled loads). Robust importers and import set transforms are related but distinct concepts.
Traps: assuming a transform map inserts duplicates - coalesce prevents that by matching on specified fields. Assuming transform scripts run in a specific order without knowing onBefore vs onAfter. And assuming staging data is automatically cleaned up - it is not unless configured. Another trap: confusing data sources (where data comes from) with transform maps (how it lands in the target table).
Worked example: To import users from a CSV, create a file data source, load it into an import set (staging table), create a transform map to sys_user with a coalesce on user_name, map columns to fields, and add an onBefore script to normalize email addresses. Run the transform and review the transform history for errors.